Centering device for pistons, &amp;c.



I. A. SCOTT. CENTERING DEVICE FOR PISTONS, &c.

APPLICATION FILED MAR. 24, I919- ;Patented May 18, 1926).

fra /57112271 bid 4,5602? UNITED gTATES PATENT JAMES ARTHUR SCQTT, OF LOS ANGELES, CALIFORNIA.

Gil-ENTERING DEVICE F03. PISTONS, 85c.

Application filed March 24, 1319.

and useful Improvements in Centering Devices for Pistons, &c., of which the following is a specification.

My object is to make a centering dev ce for pistons and the like, and my invention consists of the novel features herein shown, described and claimed.

Figure 1 is a perspective of a drillpress provided with a centering device for PlSlIOIlS and the like, in accordance with the principles of my invention, parts being broken away and shown in section.

v 2 is an enlarged sectional detail of the centering device.

Fig. is a fragmentary top plan view as seen looking in the direction indicated by the arrow 3 in 2.

Fig. is a perspective oi the uppercnd of the chuck mandrel with the gripping aws removed.

Fig. 5 is a perspective of one of the grippingaw levers.

Fig. 6 is a perspective of one of the gripping aws.

The drill bed 1 has a central opening 2. T he externally screw threaded post 3 has a flat lower end l resting upon the lat upper face of the drill bed 1,, and a shank 5 extends downwardly through the drill bed opening 2. and a set collar 6 is mounted upon the lower end of the s cket 5 against the bottom of the drill bed to hold the post 3 rigidly in place. The center cone 7 is screw seated upon the post and screwed on from the lower end before the post is mounted in place. 4- lock nut 8 is screwed up against the cone '7 to hold the cone in its adjusted position.

A bearing 9 is clamped upon the drill tand 10. ears 11 extend from the bearing a foot lever 12 is pivotally connected to re ears 11 by a bolt 13, a rod 1: is conected to the foot lever 12 in front of the olt l3, and the rod 14 extends upwardly through the socket 5. A retractile coil spring 15 is mounted around the upper end of the rod 1d. The upper end of the post 3 is shaped to produce a chuck mandrel 16, and a large bore 17 is formed from the upper end of the chuck mandrel downwardly to-near the lower end of the post, and a Specification of Letters Patent.

Patented May 18, 1926.

Serial No. 284,750.

plunger 18 is mounted in this bore 17 against the spring 15 and screwed upon the upper end of the rod 111-. T he bore 19 in which the rod ll operated is considerably smaller than the bore 17 so to form a spring seat 20 at the lower end of the bore 17 to support the spring 15. The post 3 and mandrel 16 are formed of a single piece of round cold rolled steel, or the like.

In forming the mandrel 16 the metal is cut away to form the fiat sides 21 and 22 and the recesses 23 and 2st extending diametrically relative to the bore 17 and in planes parallel with the sides 21 and 22. Pivot holes 25 and 26 are formed through the flat faces 21 and 22 and through the recesses 23 and 2a. The gripping jaw levers 2'7 and 28 are mounted in the recesses 23 and 2 1, and pivots 29 and 30 are inserted through the pivot holes and 26 and through the pivot holes 31 in the jaw levers 27 and 28. Projections 32 and extend downwardly from the lower ends of the levers 27 and 28. Leaf springs 39; and 35 are secured in the lower ends of the recesses 23 and 24 by cap screws 36 and 37 and the free ends of the springs engage behind the projections 32 and 33, the tension of the springs being exerted to throw the lower ends of the levers 27 and 28 outwardly and the upper ends of the levers inwardly.

Attaching plates 38 are formed upon the upper ends of the levers 27 and 28 and have horizontal transverse screw holes 39 and d0, as shown in Fig. 5. The gripping jaws -11 and 42 are fixed upon the upper ends of the gripping aw levers 27 and 28, each of said gripping jaws being constructed as shown in F 6. The central recess 43 is adapted to receive an attaching plate 38, there being tapped screw holes 14- and 45 at the bottom of the recess. The attaching plate 38 is placed in the recess and cap screws 4C6 and 47 a e inserted through the attaching plate and screwed into the holes dd and 45 to hold the ja rigidly upon the jaw lever. The outer faces d8 and d9 of the gripping jaw are flat and [lush with the outer face of the attaching plate 38. Rounded faces 50 and 51 extend from the outer ends of the flat faces 48 and d9. The face 52 of the gripping jaw is directly opposite the recess 43 and the face is concave in plan and beveled in cross section so as to make an expanding cam seat.

An expanding cam 53 is rigid with the plunger 18 and the ends of the cam fit the expanding cam seats 52, so that when the foot lever 12 is pressed downwardly the expanding cam is pressed downwardly to press the gripping jaws 41 and i2 outwardly, and so that when the foot lever 12 is raised the spring 15 will raise the plunger 18 to raise the cam 53, and the springs 3% and will throw the gripping jaws 41 and 42 inwardly. The piston 54c of an internal combustion engine is placed with its open end downwardly upon the cone 7, and with the expanding cam 53 passing between the wrist pin bosses; then the foot lever 12 is depressed 'to expand the gripping jaws ll and 42 to grip the inner face of the piston and center the piston; then the drill press is operated to make a center point 55 so that the piston may be centered in a lathe to machine the piston.

The principal object of centering the rough castings from the inside is to make a finished outer face concentric to the cored inner face, thereby making the wall of the finished piston of a substantially even thickness.

Various changes may be made without departing from the spirit of my invention as claimed.

I claim:

1. In a centering devicefor pistonsand the like comprising a shank adapted to be inserted downwardly through a drill bed, an externally screw threaded post extending upwardly from the shank and resting upon the drill bed, a cone, screw seated upon the post, an expanding mandrel having gripping jaws mounted on the post, and the means for expanding the jaws of the mandrel.

2. A centering device for pistons and the like comprising a shank adapted to be in serted downwardly through a drill bed, a foot lever adapted to be mounted upon a drill stand, a rod extending from the foot lever through the shank, an externally screw threaded post extending upwardly from the socket and resting upon the drill bed, a cone screw-seated upon the post, an expanding mandrel extending upwardly from the post, a plunger in the mandrel and connected to the rod, a spring for raising the plunger, jaws pivotally mounted in the mandrel and having gripping faces adapted to engage the inner .t'ace oi the piston and having cam seats, and a cam upon the plunger engaging the cam seats so that when the foot lever is depressed the gripping jaws will be expanded, and so that when the foot lever is released the gripping jaws will be contracted.

In testimony whereof I have signed my name to this specification.

' JAMES ARTHUR SCOTT. 

